A pneumatic tire is generally required to have high capacity of simultaneously satisfying various requirements of plural, different performances. In particular, a component member of a tire such as tread is keenly required to achieve both good rolling resistance properties and good wear resistance in a compatible manner. However, there have been quite a few trial-and-errors in the prior art in this connection because good rolling resistance properties and good wear resistance are basically inconsistent with each other.
Hydrated silica has been used as one of reinforcement fillers in a rubber composition applied to tire tread. In general, increase in content of reinforcement filers blended in a tire improves wear resistance of the tire to some extent but possibly deteriorates rolling resistance properties thereof and may result in poor workability due to too high viscosity of unvulcanized rubber in some applications.
In view of this, there has been developed a technique of improving dispersibility of hydrated silica particle into rubber components of a tire by employing hydrated silica having large-size primary particles, to improve rolling resistance properties of the tire. In this connection, Patent Literature 1, which noticed that use of hydrated silica having large-size primary particles possibly deteriorates storage modulus of a tire, discloses a technique of using hydrated silica of which coagulation force and the like have been controllably modified in order to improve storage modulus and reduce heat generation of a tire, with maintaining good dispersibility of hydrated silica.